This invention relates to an equipment and a method for the management of identification numbers of respective terminals in a communication system, e.g., in a push-button telephone system, in which communication of control data or speech data is carried out between a plurality of terminals and an exchange unit or a main unit (hereinafter generically called a center) whereby identification numbers of a terminal which effects communication of those data are attached to such data, and a method of implementing the same.
As a typical communication system of this kind, there is a push-button telephone system. Referring to FIG. 1, there is shown a system configuration of a push-button telephone system in which a plurality of terminals are multi-connected to one main unit.
As shown, at least one outside line 3 and a plurality of private line terminals 5.sub.1 to 5.sub.n are connected to the main unit 1. These private line terminals 5.sub.1 to 5.sub.n are multi-connected to the main unit 1 through a speech signal line 7 and a control data line 9. The main unit 1 operates when an AC power of 100 V is delivered from a connector 11 to place these private line terminals 5.sub.1 to 5.sub.n under control to thereby govern telephonic communication between these private line terminals 5.sub.1 to 5.sub.n and the outside line 3 and telephonic communication between these private terminals.
In such a telephone system employing a terminal multiconnection system, control data communicating between main unit 1 and respective private line terminals 5.sub.1 to 5.sub.n are discriminated by identification numbers (ID numbers) for every private line terminal 5.sub.1 to 5.sub.n. Namely, for example, as shown in FIG. 2, downstream data outputted from the main unit 1 toward the terminal 5 comprises a code number (hereinafter referred to as a downstream ID number) added at its first position wherein the code number includes one bit code "0" for indicating that this data is identified as the downstream data and an ID number peculiar to the terminal 5. Further, upstream data outputted from the terminal 5 toward the main unit 1 comprises a code number (hereinafter referred to as an upstream ID number) added at its first position wherein the code number includes one bit code "1" for indicating that this data is identified as the upstream data and an ID number peculiar to the terminal 5. Thus, the main unit 1 and the terminals 5.sub.1 to 5.sub.n can discriminate equipment with which they communicate.
Such ID numbers for every terminal are required to be registered by the system at the time of installation of the system or at the time of alteration of the system content such as enlargement of terminals, etc. A conventional arrangement for registering such ID numbers will now be described with reference to the arrangement of a conventional private line terminal 5 in a block form shown in FIG. 3.
The private line terminal 5 includes a CPU 13 for controlling respective components in this terminal. The CPU 13 is connected, through a bus 15, to a ROM 17 in which a control program is stored, a RAM 19 for storing data required for control, and an input/output interface 21 for relaying transmission and reception of control data to and from the respective components in the terminal. Control data from a setting switch 23 for setting an ID number, a key matrix 25 including dial keys and function keys, a hook switch 31 which is turned on/off in response to on hook/off hook of a handset 29, and a main unit interface circuit 33 for relaying communication with the main unit 1 and for delivering power supplied from the main unit 1 to respective components are received by the CPU 13 through the input/output interface 21. On the other hand, control data are transmitted through the input/output interface 21 from the CPU 13 to a main unit interface circuit 33, a speech switch 39 for selectively connecting a speech signal line 35 from the main unit interface circuit 33 to either the handset 29 or a speaker 37 for on hook speech, and a display 41 for conducting various displays such as call incoming display or calling display, etc.
The handset 29 is connected to the speech switch 39 through a speaking of speech circuit 43 having a two-wire/four-wire conversion function. Further, the speaker 37 is connected to the speech switch 39 through an output amplifier 45.
The main unit interface circuit 33 includes a speech interface unit 33a connected to the speech signal line and a data interface unit 33b connected to the control data line 9.
Registration of ID numbers is carried out by using the setting switch 23. The setting switch 23 is comprised of, e.g., a rotary switch of four bits. By manually operating this switch, ID numbers are determined in succession. The ID number determined by the setting switch 23 is inputted to the CPU 13 through the input/output interface 21. The CPU 13 outputs the ID number thus inputted to the main unit interface circuit 33 through the input/output interface 21. The main unit interface circuit 33 sends control data indicative of the ID number from the data interface unit 33b to the control data line 9. A current ID number of the terminal 5 is added to the first position of the data indicative of ID number. The ID number added control data is sent to the control data line 9 and is then received by the main unit 1. The main unit 1 recognizes which terminal sends this current control data on the basis of the ID number attached to the first position of the received data to rewrite the ID number of the terminal 5 registered in the memory assembled to provide the ID number indicated by the received data.
As stated above, in the conventional communication system, ID numbers are registered by the setting switch 23 manually operated like a rotary switch provided at each terminal. However, since a user of each terminal can arbitrarily operate such a setting switch 23, he might conduct an illegal or unjust act or deed, e.g., to alter an ID number of the terminal assigned to himself to an ID number of the terminal assigned to any other person to thereby allow the main unit to recognize as if calling of the user himself would be calling of any other person to escape the own charging, or to alter an ID number of the terminal subject to the outside line calling regulation to an ID number of the terminal where the outside line calling is permitted to thereby violate the outside line calling regulation, etc.
In view of this, an approach was proposed to to use, instead of the setting switch 23, a ROM in which ID numbers are written in advance to allow the CPU 13 to read the content recorded in the ROM to send the recorded content to the main unit 1, thereby conducting a registration. In the case of the approach using ROM, the action as stated above cannot be carried out with ease. To the contrary, where there is a need to alter ID numbers resulting from the alteration of the system content, troublesome work to exchange one ROM with another ROM is required.
A further problem is that it is troublesome to check overlapping of ID numbers within the same system even in either case of setting switch 23 or ROM.